Diabetes is characterized by: 1) enhanced platelet adhesiveness and hyperaggregability; 2) proliferation of vascular smooth muscle cells and glomerular mesangial cells and 3) defective oxidative metabolism with associated abnormalities in mitchondrial function and secondary abnormalities in basement membrane and Na+/K+-ATPase activity. Each of these abnormalities is associated with abnormal lipid metabolism. The composition of diabetic renal membranes is shifted toward more saturated, shorter chained fatty acids. In this proposal we will test the hypothesis that enrichment of cell membranes with n-3 fatty acids will affect mesangial cells and renal mitochondria in such a way as to decrease mesangial proliferation and defective renal cortical oxidative metabolism of diabetes. We will isolate renal mesangial cells from diabetic and control animals and study them in early culture passage. Mesangial cell membranes will be enriched with n-3 fatty acids. Cell activation and proliferation will be studied and compared with that of cells enriched with other individual fatty acids. We will examine the determinants of proliferation in these cells at various levels. We will measure cytosolic free calcium concentration and regulation as well as pH, and phospholipase C and protein kinase C activities in response to PDGF, PAF and IL1, C-fos and c-myc proto- oncogene expression will be characterized in cells obtained from control and diabetic animals. In addition, transcription assays of genes coding for ribsomal RNA will be performed to establish whether the response of the mesangial cell to proliferative stimuli is altered in diabetes and also to establish whether or not n-3 fatty acid enrichment can decrease the tendency toward proliferation. We will study animals made diabetic by injection of streptozotocin as well as animals with the genetic tendency toward diabetes (BB/wor strain). Diabetic animals will be fed control, n-3 fatty acid-enriched, or high beef tallow diets. Renal mitochonria will be isolated from these animals and defects in the electron transport chain including specifically NADH Coenzyme Q Reductase complex, F1-ATPase, and adenine nucleotide translocase activity associated with diabetes will be characterized. It will be determined whether or not a diet high in n-3 fatty acids results in preservation of these mitochondrial bioenergetic functions.